All vessels are susceptible to galvanic corrosion below the waterline caused by current flow in seawater between the dissimilar metals used in their construction. This can be countered by fitting sacrificial anodes close to the components susceptible to corrosion, so that these are corroded instead. However, for large vessels an Impressed Current Cathodic Protection (ICCP) system, which generates an electrical current in the seawater around the hull, cancelling out the galvanic currents, is usually a more cost-effective solution.
Both the galvanic currents causing the corrosion (including corrosion of sacrificial anodes) and the currents caused by the ICCP system can provide signatures that can be detected by other vessels and mines. For naval vessels to remain undetected, it is essential that these signatures are reduced to as low a level as possible. A good explanation of signatures and their causes is available from Aish Technologies: please contact us for more details.
In the 1980’s the signatures associated with conventional Cathodic Protection systems were targeted for reduction, and Aish Technologies was the first company in the world to equip a submarine class with a system that not only provided automatic corrosion protection, but also addressed corrosion-related signatures. Three classes of modern submarine (two in the US Navy and one in the Royal Navy) are now in service with Aish Technologies Low Signature Impressed Current Cathodic Protection (ICCP) systems, and the system has been extended into the surface fleet. As a result, Aish Technologies is the world leader in Low Signature Cathodic Protection, with more systems in service than any other supplier.
Since that first submarine fit, Aish Technologies’ Impressed Current Cathodic Protection (ICCP) systems have been subject to a regime of continuous improvement, to the point where today we can offer cost-effective, versatile and scalable systems to suit submarines and surface ships in two generic types – Aish C3P and Series 300. Superb corrosion protection is a given for both types: the difference between them lies in the degree of signature management afforded by the controller and the number of zones each controller can handle. In general, all Aish Technologies’ systems can offer the following:
• Low ripple power supplies
• LCD display interface
• Control to ± 1mV at controlling electrode
• Over 50 zones from one controller (5 zones Series 300)
• Automatic data logging option
• Individual anode control with manual override
• Compatible with a wide range of anodes
• Interface with 3rd party software (for closed loop deamping)
• High Quality silver/silver chloride reference electrodes; auto reference electrode changeover on failure
• Modular system can be split to fit available space
• Individual back-EMF measurement (to check state of anodes)
• Immediate trip if overprotection is detected (avoids hydrogen embrittlement)
For more information on Aish Technologies’ Low Signature Cathodic Protection, please see the brochure, available for download here:
It all starts with a conversation: talk to us today on +44 (0)1202 307007